


Backwards Into Hell

by GayQuasar (butxaxdream)



Category: Fire Emblem: Fuukasetsugetsu | Fire Emblem: Three Houses
Genre: Blasphemy, Everyone Is Gay, Humor, M/M, Mild Gore
Language: English
Status: In-Progress
Published: 2020-09-08
Updated: 2020-10-05
Packaged: 2021-03-06 16:28:06
Rating: Mature
Warnings: No Archive Warnings Apply
Chapters: 5
Words: 3,962
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/26361910
Author URL: https://archiveofourown.org/users/butxaxdream/pseuds/GayQuasar
Summary: Byleth knew that he was, under coercion, taking on a teaching position at Garreg Mach Monastery.Byleth did /not/ know that the students were going to be so godsdamned weird.
Relationships: My Unit | Byleth/Seteth
Comments: 10
Kudos: 25





	1. the kids ain't all right

**Author's Note:**

> This is a series of (mostly) unrelated one-shots about Byleth’s time as a professor at the monastery and his interactions with the students. While the Byleth/Seteth shenanigans--appearing in later chapters--are not going to be the singular nor greatest focus, this will be incredibly gay nonetheless and include references (explicitly or implicitly) to other pairings.
> 
> Tl;dr this is a humor fic, please enjoy.

Byleth couldn’t quite remember how he’d gotten here, only that he was alone with the dark figure crouching down on the other end of the courtyard. 

“Who’s there?” Byleth asked, squinting his eyes to perhaps get a better look. Moonlight played off noodle-like strands of golden hair. The dark blue of the Gareg Mach uniform was barely visible against the darkness of night.

“Professor.”

Dimitri’s voice sounded wrong. Low and solemn, it held none of the soft politeness that Byleth was accustomed to.

Gloved fingers curled around a clump of weeds. Dimitri’s fist tightened and then he yanked--yanked so hard that the tearing sound sent shudders through Byleth.

“Are you out of your mind, as I am, Professor?” Dimitri asked, eyes steely and unwavering as they bore into Byleth. “Are you in pain, like I am?”

“What’s wrong, Dimitri?” The prince did not answer. “Dimi--” A choking gasp tore from Byleth’s throat as, without warning, Dimitri shoved the clump of weeds and roots into his mouth. Bits and crumbles of dirt fell from his overstuffed orifice. 

At first, Byleth could only watch in numb horror as Dimitri began to chew and completely swallow his unholy meal. Then, something overcame Byleth--something primal. Rage? Indignation? The need to protect one of his students?

The fire that had earned this man the title _Ashen Demon_ \--a name that left the quivering lips of bandits in all but a whisper--was ignited once more.

“Enough, Dimitri,” Byleth said firmly, fists clenching. “Spit those weeds out.”

“Mmmnnpfhhh mmmg hurffhg.”

“Dimitri! I am your professor, and you will do as I say.”

Dimitri dropped to all fours and, with animalistic fervor, began ripping up clump after clump of weeds, dirt flying into the air with each fanatical pull.

Byleth felt his eyes water and burn, but if he were crying or not, he couldn't say. The last thing he heard before succumbing to terror and anguish was crazed laughter and… squealing.

***

Byleth jolted awake with a mangled cry. He sat up in his sweat-soaked bed, chest heaving.

Just a nightmare.

Yes, it was only a nightmare.

Letting out a sigh, he relaxed his muscles and let his head fall gently back against the pillow.

“Wow,” Sothis said from her perch near his bed, sending Byleth’s heart once more into palpitations. “You must be on some preeeeeeetty strange stuff, huh?

***

After a restless morning that followed an even more restless night, Byleth started the afternoon with lectures and lessons.

Sylvain took up riding and practiced the lance. Ingrid was his sparring partner. Ashe shot apples off the head of an expertly still and enviably passive Dedue. Annette and Mercedes took well to the Faith lessons and decided to practice on each other. Felix resigned himself to slashing away at a wooden dummy, for the dummy did not care that Felix was an emotionally inept fopdoodle, and Felix liked it that way.

Byleth wasn’t sure why, but when he took Dimitri aside for personal lessons, a feeling of openness came over him.

“Dimitri?”

“Yes, professor?”

Byleth nearly signed with relief. Yes, that was the Dimitri he’d known for three days. The soft boy he so cherished.

“I… I had the strangest dream last night.” Byleth almost chuckled. What was sillier, the dream, or the fact that he was telling Dimitri about it at all? “We were in the courtyard and you were on the ground like some animal, shoveling weeds into your mouth…”

Dimitri’s eyes widened in what could, surely, only be surprise. “But, Professor…” Then a smile crept up the corners of his mouth. “That wasn’t a dream.”


	2. stupid sexy seteth

**Summary for the Chapter:**

> Byleth falls in love and dies, all in the same day.

“Do you know of Ailell?” Seteth asked Byleth as they stood side by side pretending to be engaged with the Golden Deer’s choir performance.

Though, Seteth might not be pretending. As the Archbishop’s lapdog, his faith and devotion to Seiros seemed not only necessary, but legitimate. Also evident was his distrust of Byleth. He’d said as much the day they met.

“Enlighten me,” Byleth said, looking straight ahead as Lorenz choked on a bug that had flown into his mouth and Ignatz began crying uncontrollably, but for reasons seemingly unrelated to what Lorenz was going through.

“It is known as the Valley of Torment, but this was not always so. It once thrived with life and light. However, after witnessing humanity’s corruption and sin, the Goddess was filled with rage. She cast judgment upon Ailell, scorching it with her divine fury, leaving it a hot and desolate place. I tell you this as a warning. For those who go against the Goddess, nothing awaits but anguish and destruction.” He turned. “Do you follow, _Professor_?”

It was at that moment that Byleth decided one day he was going to absolutely rail that man.

Then the mood was broken when Raphael doubled over on stage, his face going green. Marianne started hugging herself and rocking back and forth. Hilda’s hair caught fire from one of the candles. Claude was suddenly nowhere to be seen. 

With more pressing matters at hand, Byleth decided he could think about Seteth’s hole another time.

***

“Just give me the word, Lady Edelgard.”

“No, it’s quite alright, Hubert.”

Edelgard was trying to focus on her Sweet Bun Trio, not the violent urges of her over-eager retainer.

“I am but a tool for you to use,” Hubert continued. “You need only say the command, and I shall obey.”

“There’s really no need, Hubert.”

The gangly, ghoulish man slithered closer and hissed in Edelgard’s ear, “Please, let me _cut_ him, Lady--”

Edelgard threw her fork down. “For **fuck’s** sake, Hubert.” 

Byleth, who was just getting up from his own meal, couldn’t help but overhear their conversation. This was not the first time since coming to Garreg Mach that Hubert von Vestra had threatened him.

“Well met, Edelgard,” he interrupted. “And you as well, Hubert. I suppose.” 

“Greetings, Professor,” Edelgard said, courtly as usual. “Ah, I see that you’ve already had your supper. I was hoping that we might get a chance to talk.”

“No!” Hubert’s ghastly protest. “We mustn’t invite him to our table, Lady Edelgard, we mustn’t--”

“ _Silence_ , Hubert.”

On command, Hubert immediately shut his mouth. Slinking back, he gave Edelgard and Byleth room, but all the while, his beady eyes watched Byleth with venomous scrutiny. 

“Perhaps we could dine together tomorrow?” Byleth suggested.

“I look forward to it, Professor.”

Byleth gave the pair one last glance as he walked off, and he swore he saw Hubert stick out his tongue and hiss.

***

While making his rounds, Byleth spotted Ferdinand von Aegir on the bridge leading to the Cathedral. Or rather, Ferdinand spotted Byleth.

“Oh, Professor!” he called, waving Byleth over. Taking the bait, Byleth approached the pretty redhead. “Were you able to watch the Golden Deer’s performance earlier? Though the Black Eagles could have done much better, it was nonetheless a true delight.”

“Was it?”

“While you are here…” There was something mischievous, or perhaps devious, about Ferdinand’s smile. “Might I enlighten you on the Empire’s great noble families?”

“I don’t know, Ferdi--”

“Excellent!” Ferdinand cleared his throat. “There is Caspar’s father, Count Bergliez, Minister of Military Affairs…”

Byleth began taking steps backward.

“...Then there is Linhardt’s father, Count Hevring, the Minister of Domestic Affairs.”

Byleth’s heels bumped up against the stone railing.

“...Bernadetta’s father, Count Varley, is the Minister of Religious Affairs...”

Byleth turned and looked over the edge. The fall was so far. The abyss was so deep.

“...Hubert’s father, Marquis Vestra, is the Minister of the Imperial Household…”

He turned back to Ferdinand one last time, eyes pleading. But Ferdinand’s mouth kept moving.

“Then there is **my** father! Duke Aegir, Prime Minister of the--!”

Byleth jumped off the bridge.

**Notes for the Chapter:**

> Thanks to my sexy little beta reader @jotarovapes ;)


	3. but if YOU'RE gay and I'M gay WHO'S FLYING THE PEGASUS

Birds chirped happily as they fluttered about, soaring with the gentle breeze. Plants drank up beams of sunlight. The monastery cats stretched out and napped on the warm grass.

Byleth hated all of it.

“And how have you been adjusting to life at the monastery?” Rhea asked, stirring her tea.

“Well enough,” Byleth said, stony visage betraying none of the discomfort he felt.

Once again, Byleth found himself at Rhea’s mercy. This time, he’d been coerced into an intimate tea date. Why she was so fascinated with him, he couldn’t fathom. The feeling was certainly not mutual. From the moment they met just a few weeks ago, something about Rhea gave Byleth a bad feeling. Maybe it was the way she smelled like secrets and theocratic authoritarianism. 

“I’m glad to hear it,” Rhea said, smiling. “Jerlat was worried about how to might take to being a professor here, however, you seem like quite a natural…”

Byleth’s attention on Rhea waned considerably when out of the corner of his eye he saw a lone wyvern circling the sky. Hanging off its back and flopping about like a ragdoll was a garish corpse clothed in black, its skin pale as death--

No, wait. That was just Hubert.

Why Hubert was passed out on the back of a wyvern, Byleth did not know, but it was already infinitely more interesting than anything Rhea was saying. Letting the Archbishop’s words fall on distracted ears, he watched Hubert’s body flail in the wind--until it slipped off the wyvern and fell like a sack of apples toward the ground.

“Is something the matter?” Rhea asked, just a touch of edge in her voice.

From down below, Byleth heard a loud, “What the--?  _ GAH _ !” followed Dedue crying out, “Your Highness!”

Byleth shook his head, turning back to face Rhea “Nothing at all, Archbishop.”

***

“I have something to ask of you.”

“I’ll do it.”

Standing across from Seteth in the Advisory Room--or the  _ Bitch Kitchen _ as Byleth called it, because Seteth spent much of his time there--Byleth struggled with lust. 

There was nothing about Seteth that was particularly sensual or arousing. He was handsome, yes, but Garreg Mach had no shortage of handsome men. Was it his personality, then? Judgmental, untrusting, uptight, stiff. So very stiff. The very definition of overbearing. 

Seteth paused, then quirked his brow. “You don’t even know what I’m going to say.”

“Correct.”

That had to be it.

Byleth wanted to tear down Seteth’s walls, wipe that pissy little look off his face, bend him over the desk, and teach him whom he  _ really  _ ought to worship.

_ Keep it in your trousers, you lecherous fool! _ Sothis’ voice rang in his head, interrupting his fantasy.

With elbows propped up on the desk, Seteth leaned in to rest his chin against his entwined hands. Byleth felt like he was being studied. “Professor, are you blindly agreeing to whatever it is I say?”

“Yes.”

Seteth’s bushy green eyebrows knitted together as he narrowed his eyes in consideration. Then he said very quickly, “Do you swear fielty to the Church of Seiros?”

“Craving my loyalty, Daddy?”

“Excuse me?”

“You had something to ask of me,” Byleth reminded him.

“Yes, I… I did. Now, I am not so sure.”

“When you’ve rediscovered what it is you want, send for me. Otherwise, I have students to tend to.” Byleth turned curtly on his heel and walked away, leaving a baffled Seteth all alone.

***

“Thank you for coming,” Byleth told Sylvain as the student stepped into the empty classroom. Please, sit.”

“No problem, Professor. The Sylvain always comes when he’s called. Usually.” Waltzing past all the perfectly suitable chairs, Sylvain propped himself up on Byleth’s desk. He spread his legs wide, leaned back casually, and gave his professor a playful smile. “Now, how much trouble am I in?”

Byleth let out a steady sigh, trying not to think about the student papers that were being crumpled underneath Sylvain’s ass. “Sylvain, I find so many things about you challenging.”

Sylvain’s stupid smirk didn’t falter. “Oh?” 

Unclenching his jaw, Byleth began counting off on his fingers. “You skip lessons, you daydream in class, you don’t take your work seriously, and the way you treat women is deplorable.”

“Look, I completely agree with all of that.  _ Except  _ the last part. I don’t treat women poorly, alright? I just know how to play their game better than they do.”

“Right. Well, if I can’t sway your misogynistic tendencies, allow me to reiterate the importance of your studies.”

Sylvain leaned back further, appraising his professor. “Ahh, I see. It’s because that mock rivalry battle is coming up, right? You’re the new professor and you want to win because you’ve got a lot to prove. I get it.”

“Do you?”

He sat up straight, grabbing and shaking Byleth’s shoulder as an old pal might. “Don’t worry about it, Professor. We’re not gonna lose. So I might slack off. But I put in the effort where and when it really matters. Trust me.” He hopped off the desk. “Alright, well, good talk, my man.”

“Sylvain, just one more thing.”

Sylvain turned, his hand on the door. “Yeah?”

“Why are you naked?”

**Notes for the Chapter:**

> Note: The idea of Hubert passing out while flying is courtesy of @jotarovapes and my brother @SovietRay, both of whom are always hilarious. Please check out their fics! Jo writes great 3H smut and Ray does SFW League of Legends!
> 
> "Bitch Kitchen" joke courtesy of @jotarovapes as well! 
> 
> Me: Do either of you know what that little room connected to Rheas chambers is called? Seteth is usually there  
> Jo, immediately: the bitch kitchen


	4. the horny chapter

**Summary for the Chapter:**

> Gay thirst.

**Notes for the Chapter:**

> Gore mention!

Seteth did not know how he’d ended up in his office, just that Byleth was sprawled out on the desk and dressed in Sothis’ provocative regalia. That rich, navy dress with its threaded, gold ornamentation. Peaks at a soft, flat chest and a smooth stomach.

Seteth swallowed, as suddenly there was an abundance of saliva in his mouth. “...What is the meaning of this?”

“Seteth,” Byleth said, lifting his leg and putting on full display his shapely thigh, “I have something to ask of you.” 

“N-No, I…” Why was Seteth’s face so hot? Why were his loins burning so? He barely knew this man!

Byleth twisted around until he was perched on the edge of the desk and facing Seteth. He spread his legs, and Seteth’s eyes could not help but dart down and notice the visible bulge.

“Teach me about wyverns, pretty daddy.”

“ _ Daddy _ ?!” Seteth stumbled back, nearly tripping over his chair. He shielded his eyes, not able to look away from Byleth’s groin any other way. “No! O-Only Cethleann can call me such a thing!”

“Saint Cethleann?”

Seteth went pale. Had he really just exposed the secret he’d kept for centuries? To this infidel, of all people?! 

“W-Who?” Seteth stammered. “I don’t know a Cethlean! I don’t know what you’re talking about at all! I--I--!”

Seteth jolted awake with a mangled cry. He sat up in his sweat-soaked bed, chest heaving.

Just a nightmare.

Yes, it was only a nightmare.

Letting out a sigh, he relaxed his muscles and let his head fall gently back against the pillow. But then his eyes shot open when he heard an all too familiar voice in the bed beside him.

“My, my!” said Hanneman, naked and covered in bite marks. “You must be on some pretty strange substances, hmm?”

***

Byleth had just finished up a lecture when Dedue approached him in the courtyard.

“Professor, do you have a moment?”

“For you, Dedue? Of course. Anything for you.”

“I would like for you to accept my seed.”

There was a long, painful pause between them.

“Your… seed?”

“I know it is not much, but I want you to take it.” Dedue lifted a hand, extending his closed fist toward Byleth. Noticing his professor had just gone silent, Dedue went on. “Do you not want my seed? I apologize for troubling you.”

Of course, Byleth wanted it. Dedue had the sort of figure that artists worshipped with paintings and sculptures.

No, consent wasn’t the issue.

Byleth stared at Dedue’s big, strong hand and said slowly, “No, I’m just… not sure if that will fit…” Then he  held his breath as Dedue opened his fist to reveal--

A tiny seed in the palm of his hand.

“A garden vegetable,” Deduce explained. “I noticed you frequenting the greenhouse, so I thought you might like to grow this.”

As the familiar pang of disappointment filled his chest, Byleth took Dedue’s hand, seed and all, in his own and whispered, “ _ Thank you _ .”

***

Prowling the monastery grounds at night was one of the few things Byleth enjoyed. The air was quiet, the mood was peaceful, and he only had to listen to the cats shrieking and mating maybe twice a week.

His good mood was disrupted, however, when he passed a burly fellow that night who said, “Hey, pal! I’m gonna fuck your mom, alright?” and nothing else. Which was weird, but certainly not the weirdest thing that had been said to him within the halls of Garreg Mach Monastery.

Later, Byleth noticed another person stalking around in the dark. As he got closer, he could see their wheat-colored hair pulled back into a long tail.

“Jeritza?”

It was the handsome, masked teacher who always sounded like he was in the process of falling asleep. 

“Jeritza… is not here…” The man turned around and Byleth lifted his lantern. Flames played against pale skin and beads of sweat. Jeritza’s jaw was clenched, and his chest heaved with labored breaths.

A shiver crept up Byleth’s spine. “Then you must be Jeritza’s sickly twin brother.”

“I dream of death,” Jertiza sighed, seemingly out of nowhere. “Of rivers of blood. Of flesh--cut and torn and ripped apart. Of entrails and viscera raining down from the sky.” The more Jeritza spoke, the more excited and needy he became. “I grasp the fresh, writhing organs and drag them across my bare chest, tainting my body with blood and fluids--”

“Hey? What the fuck?” 

Before Byleth could react, Jeritza pounced on him. They crashed to the ground and the man’s hands were around his neck. Byleth struggled but could do nothing against the powerful, rabid man straddling and throttling him. He could only stare into those wild eyes, vision starting to go black from the crushing pressure against his windpipe.

It was too much. He was so close.

Byleth’s hips jerked forward wildly. 

Jeritza stopped. His grip loosened. He stared down at Byleth. “Did you just…?”

Byleth let out a shuddering gasp and croaked, “A little bit, yes.”

Jeritza slowly got up, leaving Byleth panting on the ground. “I win… This time…” And he walked off into the night, mumbling more nonsense about blood and guts.


	5. rat king, king of the rats

**Summary for the Chapter:**

> Byleth discovers something terrifying in Dimitri's room.

“Take the shot, Ashe.”

“A-Alright, Professor…!”

Ashe let loose the bowstring. His arrow flew across the training yard, toward the target--

And missed completely, landing instead in Dimitri’s thigh. The prince staggered at the sudden shock. Growling at the pain, he punched the stone wall.

Ashe dropped his bow and let out a horrified squeal as he went pale--which was impressive, as Byleth hadn’t thought it possible that the boy could get any whiter than he already was. 

“Y-Your Highness!”

“I-It’s quite alright, Ashe!” Dimitri said through grit teeth. “I’m fine, really…!”

“Your Highness!” Dedue fell to his knees next to Dimitri. “Please, allow me to suck the poison out.”

“ _ What _ **_poison_ ** ?”

But Dedue already had his lips on the wound.

“Interesting,” Byleth said, then turned back to Ashe. “Please, try again.”

“O-Okay, Professor, if you say so…!” Ashe nocked another arrow and, with hands even shakier than before, let it fly.

It whooshed through the air and landed dead-center in the bullseye.

But perhaps Ashe’s nerves had granted him abnormal strength, for the arrow did not just hit the bullseye, it tore completely through the wooden target and out the other side. Sylvain, oblivious to peril as he tormented his classmates, got a rude awakening when an arrow landed in his buttocks. He yelped and spun around.

“Sheesh, Ashe! If you really wanted to shoot something into my ass, you could have just asked--”

His horrendous flirtation was cut short with a scream as Felix yanked the arrow out.

It had only been thirty minutes, buy Byleth was already beginning to wonder how his house was ever going to win the upcoming mock battle.

***

"Hey, Teach!" Claude waved Byleth down as the professor headed for the greenhouse. 

Byleth nodded. "Well met, Claude." That characteristic little smile played on Claude's lips. 

"I heard you and your class were on the training grounds all morning. Sounds like someone's been preparing for our battle." A wink.

"It was a long morning," Byleth said, letting the tired stoicism in his voice speak for itself.

"Say, Teach," Claude ventured, "you been to the bathroom lately?"

Byleth stared at him for a moment. "Come again?"

"Caught the stomach bug lately? How about a really bad run-in with fish and bean soup? Anything that might have lead to excessive vomiting and-or painful--"

Byleth bristled and said quickly, "No, I haven’t--should I have?"

"Who knows?" Claude shot him another wink. "Let’s just say I have an unquenchable curiosity when it comes to these things. So, how often do you use the toilet in a single day? You can give me an average--"

"Stop."

Claude put his hands up. "Look, I didn’t mean to pry." Except he certainly did. "I just want you to know that you can come to me to talk about any and all of your bathroom encounters. Good or bad. I'm all ears. Really. Any time."

"Thank you, Claude," Byleth said, brushing past him and making a break for the greenhouse.

***

By the pond, Byleth spotted Flayn, Seteth’s little sister for whom he had particularly strong paternal instincts. She carried a large fish in her hands, though Byleth was pretty sure it was already dead.

"Greetings, Flayn,” Byleth said on his approach. “That's quite the catch you have."

Flayn was the key to Seteth’s heart. If Flayn liked him, Byleth might actually have a chance with her brother. Seteth’s cock was surely worth the trouble.

Flayn beamed. "Oh, hello, Professor! This fish was actually a gift from Catherine. I am not… particularly good at fishing myself, but fish is one of my favorite foods!"

With that, she opened her mouth and took a big bite out of the raw fish, tearing its head clean off. Byleth watched, too shocked to even speak, as Flayn chewed her snack.

"Mnnfgh snerghh mmnb?" Flayn said. "Hmnnggph murph shmch."

"Flayn!"

The sweetly familiar, prudish voice snapped Byleth out of his daze. Seteth had spotted them on his way out of the dining hall was storming over. No doubt he was going to reprimand his sister for stuffing her maw with uncooked fish.

"Flayn," Seteth chided again once he reached them, his cheeks showing a soft blush.  Anger. Disappoint. Surely, was appalled by his sister.  "Flayn, what have I told you about talking with your mouth full?"

***

Lantern in hand, Byleth headed up to the student's quarters. He figured it was only right to check up on Dimitri, as he was partially responsible for the arrow that landed in the prince's leg. 

At this hour, the halls were empty and quiet. Byleth could hear low, muffled talking from behind some doors, but most students were asleep or quietly masturbating. A select few were not as quiet, Byleth thought, as he recounted the moans, hissing, and horse noises he'd heard from Ferdinand’s room last week.

As Byleth approached Dimitri's room, a different sound caused his ears to prick--scurrying. Little clawed feet scratching against floorboards.

Moving further down the hall, he realized the noise was coming from inside Dimitri’s room. The door to the prince’s quarters was open just a crack. Byleth crept closer and peeked inside. 

What he saw petrified him.

Dimitri sitting at his desk covered nearly head-to-toe in rats--rats crawling up and down his body, scurrying around his floor, nestling into his stringy hair.

“Yes, my subjects… My beautiful subjects…” Dimitri’s haggard, unhinged voice sent chills through Byleth’s body. “Love your king! Worship your king!” Dimitri threw his head back, and from his mouth erupted bubbling, voracious laughter that bordered on pure lunacy.

As soon as Byleth could breathe again he ran to his own quarters and never looked back. 

**Notes for the Chapter:**

> I'm sorry for what I did to Claude.


End file.
